Burner for fabricating optical fiber preform

ABSTRACT

A burner used for fabricating an optical fiber perform is disclosed. The burner includes a burner housing, a first body formed with a plurality of spraying ports, and a second body aligned in a length direction of the first body. At least a part of the first body is accommodated in the burner housing. At least a part of the second body is accommodated in the burner housing. An oxidizing agent is fed into the second body along an outer peripheral surface of the second body and a fuel is fed into the second body along an inner peripheral surface of the first body. The oxidizing agent is uniformly mixed with the fuel in the first body and a mixture thereof is exhausted to an exterior through the spraying ports. The fuel and the oxidizing agent are separately fed into the burner and mixed with each other in the burner, thereby preventing the backfire phenomenon. Since the mixture of the fuel and the oxidizing agent is sprayed to the exterior after the fuel has been sufficiently mixed with the oxidizing agent in the burner, it is possible to obtain the perfect combustion for the mixing gas.

CLAIM OF PRIORITY

This application claims priority to an application entitled “Burner ForFabricating Optical Fiber Preform,” filed with the Korean IntellectualProperty Office on Feb. 4, 2005 and assigned Serial No. 2005-10564, theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical fiber. More particularly,the present invention relates to an apparatus for fabricating silicaglass such as an optical fiber preform.

2. Description of the Related Art

In general, an optical fiber preform is fabricated using a vapor-phasedeposition method or a sol-gel method. According to the sol-gel method,a liquid-phase raw material is input into a mold. The mold is heated sothat the liquid-phase raw material is changed into a gel-phase material.The gel-phase material is then sintered forming fabricating silicaglass. The sol-gel method is performed under a low temperatureatmosphere, which reduces the manufacturing cost of the silica glass. Inaddition, this also enables the composition of the silica glass to beeasily adjusted.

The vapor-phase deposition method includes a modified chemical vapordeposition (MCVD) method, a vapor-phase axial deposition (VAD) methodand an outside vapor deposition (OVD) method. According to thevapor-phase deposition method, a solid optical fiber preform isfabricated through a vapor reaction under a high-temperature atmosphereof about 1800° C. The vapor-phase deposition method requires expensivemanufacturing equipment in order to fabricate the optical fiber preformwhile causing low productivity. However, the vapor-phase depositionmethod can obtain a high-quality optical fiber preform. When performingthe vapor-phase deposition method, a burner is used in order to promotedeposition of an evaporated raw material.

As shown in FIGS. 1 and 2, conventional burners 10 and 20 used forfabricating optical fiber preforms include combustion units 11 and 21formed with a plurality of spraying ports 12 and 22, which are alignedwith a predetermined pattern. The conventional burners 10 and 20 alsoinclude at least one pair of pipes 13, 15, 23, and 25 connected to thecombustion units 11 and 21 in order to feed fuels and oxidizing agentsinto the combustion units 11 and 21. The pipes 13, 15, 23, and 25 areconnected to fuel storage tanks and oxidizing agent storage tanks (notshown) and integrally unified at predetermined positions of the burners10 and 20. Mixing regions 17 and 27 are formed in the unified portionsof the pipes to mix the fuels with the oxidizing agents before they arefed into the combustion units 11 and 21. Since the fuels are uniformlymixed with the oxidizing agents before they are fed into the combustionunits 11 and 21, the burners 10 and 20 can obtain perfect combustion ata relatively high-temperature.

However, if the temperature of the mixture exceeds the combustion pointor if ignition occurs by an ignition source the conventional burners 10and 20 may cause explosion or combustion in the mixing regions beforethe mixture of the fuels and the oxidizing agents are fed into thecombustion units. Such a phenomenon is called a “backfire.” In order toprevent the backfire, one proposed method is to suppress any temperatureincrease in the mixing regions and control a cut-off order of the fuelsand the oxidizing agents when turning off the burners, but the backfireproblem still remains.

FIG. 3 shows another conventional burner 30 for fabricating the opticalfiber preform. As shown in FIG. 3, the conventional burner 30 includes acombustion unit 31 formed with a fuel injection port 33 and an oxidizingagent injection port 35. The fuel and the oxidizing agent are injectedinto the combustion unit 31 through the fuel injection port 33 and anoxidizing agent injection port 35. In this state, the fuel is exhaustedthrough an exhaust port 32 formed at a center of the combustion unit 31and the oxidizing agent is exhausted around the fuel. The fuel is mixedwith the oxidizing agent in a mixing region 37 formed at an end of thecombustion unit 31 so that the mixture of the fuel and the oxidizingagent is burned in the mixing region 37.

Such a conventional burner is called a “dispersing burner.” According tothe dispersing burner, the fuel and the oxidizing agent are separatelyexhausted from the combustion unit and mixed with each other at an endof the combustion, so explosions only rarely occur. However, since thefuel and the oxidizing agent may be burned even if the fuel is notsufficiently mixed with the oxidizing agent, density of a mixing gas isirregularly formed in flames exhausted from the conventional burner.This causes unstable flames and imperfect combustion.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to a burner for fabricatingan optical fiber preform, capable of preventing a backfire phenomenon.

Another aspect of the present invention relates to a burner forfabricating an optical fiber preform, capable of obtaining stable flamesand a perfect combustion by allowing fuels to be sufficiently mixed withoxidizing agents.

One embodiment of the present invention is directed to a burner used forfabricating an optical fiber perform. The burner includes a burnerhousing; a first body formed with a plurality of spraying ports, atleast a part of the first body being accommodated in the burner housing;and a second body aligned in a length direction of the first body, atleast a part of the second body being accommodated in the burnerhousing, an oxidizing agent being fed into the second body along anouter peripheral surface of the second body and a fuel being fed intothe second body along an inner peripheral surface of the first body. Theoxidizing agent is uniformly mixed with the fuel in the first body and amixture thereof is exhausted to an exterior through the spraying ports.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and embodiments of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side sectional view illustrating a conventional burner forfabricating an optical fiber preform;

FIG. 2 is a side sectional view illustrating another conventional burnerfor fabricating an optical fiber preform;

FIG. 3 is a side sectional view illustrating still another conventionalburner for fabricating an optical fiber preform;

FIG. 4 is a side sectional view illustrating a burner for fabricating anoptical fiber preform according to a first embodiment of the presentinvention;

FIG. 5 is a plan view of a burner shown in FIG. 4;

FIG. 6 is a side sectional view illustrating a burner for fabricating anoptical fiber preform according to a second embodiment of the presentinvention; and

FIG. 7 is a plan view of a burner shown in FIG. 6.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings. For the purposes of clarity andsimplicity, a detailed description of known functions and configurationsincorporated herein will be omitted as it may obscure the subject matterof the present invention.

FIG. 4 is a side sectional view illustrating a burner 100 forfabricating an optical fiber preform according to a first embodiment ofthe present invention and FIG. 5 is a plan view of the burner 100 shownin FIG. 4.

As shown in FIGS. 4 and 5, the burner 100 includes a burner housing 101,a first body 102, a second body 103, and a center plug 104.

The first and second bodies 102 and 103 include, at a sidewall, at leastone pair of injection ports 113 and 115. Fuels and oxidizing agents arefed into the burner housing 101 through the injection ports 113 and 115.

The first body 102 is formed at one end with a plurality of sprayingports 121. The first body 102 is formed at an inner portion with acavity having a predetermined size, which is coupled to the sprayingports 121.

The second body 103 is accommodated in the burner housing 101 whilebeing aligned in a length direction of the first body 102. The firstbody 102 is spaced from the second body 103 by a predetermined distancein order to form an oxidizing agent port 123 therebetween. The oxidizingagent port 123 is formed along an outer circumferential portion of thesecond body 103. A passage is formed between an outer peripheral surfaceof the second body 103 and an inner peripheral surface of the burnerhousing 101 in order to connect one of the injection ports 113 and 115with the oxidizing agent port 123. The oxidizing agent is fed into theburner 100 through one of the injection ports. The oxidizing agent thenmoves along the outer peripheral surface of the second body 103 andflows into the first body 102 through the oxidizing agent port 123. Theinjection port 113 connected to the oxidizing agent port 123 is calledan “oxidizing agent injection port.” The oxidizing agent port 123 isinclined towards the first body 102.

The other injection port 115 extends into the second body 103 to allowthe fuel to be injected into the second body 103. The other injectionport 115 is called a “fuel injection port.” The fuel injected into thesecond body 103 through the fuel injection port 115 is fed into thefirst body 102 through the second body 103.

The center plug 104 is inserted into the second body 103 so that one endof the second body 103 is closed by the center plug 104. The center plug104 is formed at an outer peripheral portion thereof with a slot havinga predetermined size, so that a cavity 141 is formed between the centerplug 141 and the second body 103 when the center plug 104 has beenaccommodated in the second body 103. The cavity 141 is connected to thefuel injection port 115 such that the fuel can be fed into the firstbody 102 through the cavity 141. A fuel exhaust port 143 is formedbetween the cavity 141 and an end of the second body 103. The exhaustport 143 is spaced from the end of the second body 103.

When the oxidizing agent is fed into the burner 100, the oxidizing agentis introduced into the first body 102 through the oxidizing agent port123 while generating a high-speed fluid flux. Such a high-speed fluidflux caused by the oxidizing agent introduced into the first body 102may form a low-pressure region 131 between the fuel exhaust port 143 andthe end of the second body 103. Due to the low-pressure region, the fuelprovided in the cavity 141 is fed into the first body 102 through thefuel exhaust port 143. The fuel is fed into the first body 102 throughthe fuel exhaust port 143 and the low-pressure region 131 due todifferential pressure between the low-pressure region 131 and the cavity141. The oxidizing agent is mixed with the fuel in a mixing region 129formed in the first body 102. As the oxidizing agent and fuel arecontinuously fed into the burner 100, pressure of the mixing region 129may rise, so that mixing gas is exhausted to an exterior due todifferential pressure between the mixing region 129 and the exterior.

The burner 100 is formed at an inner portion thereof with the mixingregion 129 in which the fuel is mixed with the oxidizing agent. Themixture of the fuel and the oxidizing agent is sprayed to the exteriorthrough the spraying ports 121, so the backfire phenomenon may notoccur. In addition, since the fuel is sufficiently mixed with theoxidizing agent in the burner 100 before they are exhausted out of theburner 100, it is possible to obtain stable flame and perfectcombustion.

FIG. 6 is a side sectional view illustrating a burner 200 forfabricating an optical fiber preform according to a second embodiment ofthe present invention, and FIG. 7 is a plan view of the burner 200 shownin FIG. 6.

As shown in FIGS. 6 and 7, the burner 200 includes a burner housing 201,a first body 202, a second body 203, a center plug 204, and a guidehousing 205.

The burner housing 201 receives the first and second bodies 102 and 103therein and includes at least one pair of injection ports 113 and 115 ata sidewall. Oxidizing agents are introduced into the burner housing 201through the injection port 213. The injection port 213 is called a“first oxidizing agent injection port.”

A plurality of spraying ports 221 a and 221 b are formed at one end ofthe first body 202, which are coupled with the burner housing 201. Thefirst body 202 includes, at an inner portion thereof, a cavity having apredetermined size, in which the spraying ports 221 a and 221 b arecommunicated with the cavity. In contrast to the first embodiment, inwhich one end of the first body 102 is closed, In the second embodiment,one end of the first body 202 is closed by the center plug 204 extendinglengthwise along the burner housing 201. The spraying ports 221 a and221 b are formed at an end of the center plug 204. In addition, thecavity formed in the first body 202 is positioned between an innerperipheral surface of the first body 202 and an outer peripheral surfaceof the center plug 204.

The second body 203 is inserted into the burner housing 201 while beingaligned in a length direction of the first body 202. The first body 202is spaced from the second body 203 by a predetermined distance in orderto form an oxidizing agent port 223 therebetween. The oxidizing agentport 223 is formed along an outer circumferential portion of the secondbody 203. A passage is formed between an outer peripheral surface of thesecond body 203 and an inner peripheral surface of the burner housing201 in order to connect the first oxidizing agent injection port 213with the oxidizing agent port 223. The oxidizing agent is fed into theburner 200 through the first oxidizing agent injection port 213, movesalong the outer peripheral surface of the second body 203 and flows intothe first body 202 through the oxidizing agent port 223. The oxidizingagent port 223 is inclined towards the first body 202.

A first fuel injection port 215 is formed at an outer peripheral surfaceof the second body 203 and is connected to an inner portion of thesecond body 203. The fuel introduced into the second body 203 throughthe first fuel injection port 215 is fed into the first body 202 throughthe second body 203.

The center plug 204 is inserted into the second body 203 in order toclose one end of the second body 203. The center plug 204 is provided atan outer peripheral surface thereof with a rib extending in acircumferential direction of the center plug 204. A cavity 241 is formedbetween the center plug 204 and the second body 203 when the center plug204 has been inserted into the second body 203. The cavity 241 iscoupled with the first fuel injection port 215 so that the fuel is fedinto the first body 202 through the cavity 241. A fuel exhaust port 243is formed between the cavity 241 and the end of the second body 203, inwhich the fuel exhaust port 243 is spaced from the end of the secondbody 203.

As described above, the center plug 204 extends lengthwise along theburner housing 201 and the end of the center plug 204 closes the end ofthe first body 202. In addition, plural spraying ports 221 a and 221 bare formed at the end of the center plug 204 to allow the cavity formedin the first body 202 to be coupled to the exterior.

In addition, one of the spraying ports 221 a and 221 b linearly extendsalong the center of the center plug 204 so that the spraying port(herein, the spraying port 221 b) is aligned at the center of the pluralspraying ports. The spraying port 221 b formed at the center of thecenter plug 204 is coupled to a second fuel injection port 245 formed atthe outer peripheral surface of the center plug 204.

In the meantime, the guide housing 205 receives the burner housing, thefirst body, the second body and the center plug therein. The guidehousing 205 is formed with a perforation hole coupled to the first andsecond fuel injection ports 215 and 245 and the first oxidizing agentinjection port 213. In addition, the guide housing 205 has a secondoxidizing agent injection port 219. The oxidizing agent can be fed intothe burner through the second oxidizing agent injection port 219separately from the first oxidizing agent injection port 213. Theoxidizing agent fed into the burner through the second oxidizing agentinjection port 219 is introduced into the cavity formed between theinner peripheral surface of the burner housing 201 and the outerperipheral surface of the first body 202 while flowing along the outerperipheral surface of the burner housing 201. The first body 202 isformed with a plurality of guide holes 221 c, which are coupled to thecavity formed between the burner housing 201 and the first body 202.Referring to FIG. 7, the guide holes 221 c aligned in pattern around thespraying ports 221 a and 221 b. In this embodiment, the pattern iscircular.

When the oxidizing agent is fed into the burner 200 through the firstoxidizing agent injection port 213, the oxidizing agent is introducedinto the first body 102 through the oxidizing agent port 223 whilegenerating a high-speed fluid flux. Such a high-speed fluid flux causedby the oxidizing agent introduced into the first body 202 may form alow-pressure region 231 between the fuel exhaust port 243 and the end ofthe second body 203. Due to the low-pressure region 231, the fuelprovided in the cavity 241 is fed into the first body 202 through thefuel exhaust port 243. The fuel is fed into the first body 202 throughthe fuel exhaust port 243 and the low-pressure region 231 due todifferential pressure between the low-pressure region 231 and the cavity241. The oxidizing agent is mixed with the fuel in a mixing region 229formed in the first body 202. As the oxidizing agent and fuel arecontinuously fed into the burner 200, pressure of the mixing region 229may rise, so that mixing gas is exhausted to the exterior due todifferential pressure between the mixing region 229 and the exterior.

The burner 200 is formed at an inner portion thereof with the mixingregion 229. The fuel is mixed with the oxidizing agent and the mixtureof the fuel and the oxidizing agent is sprayed to the exterior throughthe spraying ports 221 a and 221 b, so the backfire phenomenon may notoccur. In addition, since the fuel is sufficiently mixed with theoxidizing agent in the burner 200 before they are exhausted out of theburner 100, it is possible to obtain stable flame and perfectcombustion.

In addition, the fuel and the oxidizing agent fed into the burner 200through the second fuel injection port 245 and the second oxidizingagent injection port 219 are exhausted to the exterior through thespraying port 221 b formed at the center of the first body 202 and theguide holes 221 c. The fuel fed into the burner 200 through the secondfuel injection port 245 is exhausted out of the first body 202 whilebeing burned together with mixing gas formed in the first body 202. Inaddition, the oxidizing agent exhausted to the exterior through theguide hole 221 c may flow along a peripheral area of the mixing gas toallow the mixing gas to be stably burned. A part of the oxidizing agentcan be mixed with the mixing gas in order to adjust a mixing ratio ofthe mixing gas.

As described above, the fuel and the oxidizing agent are separately fedinto the burner and mixed with each other in the burner, therebypreventing the backfire phenomenon. In addition, since the fuel is mixedwith the oxidizing agent in the burner just before the mixing gas issprayed to the exterior from the burner, the backfire phenomenon may notoccur. Furthermore, since the mixture of the fuel and the oxidizingagent is sprayed to the exterior after the fuel has been sufficientlymixed with the oxidizing agent in the burner, it is possible to obtainthe perfect combustion for the mixing gas.

While the invention has been shown and described with reference tocertain embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the invention as definedby the appended claims.

1. A burner used for fabricating an optical fiber preform, the burnercomprising: a burner housing; a first body formed with a plurality ofspraying ports, at least a part of the first body being accommodated inthe burner housing; and a second body aligned in a length direction ofthe first body, at least a part of the second body being accommodated inthe burner housing, wherein an oxidizing agent can be fed into thesecond body along an outer peripheral surface of the second body and afuel can be fed into the second body along an inner peripheral surfaceof the first body, and wherein the oxidizing agent is uniformly mixedwith the fuel in the first body and a mixture thereof is exhausted to anexterior through at least one of the plurality of spraying ports.
 2. Theburner as claimed in claim 1, wherein the oxidizing agent is introducedinto the first body through an injection port formed between an end ofthe first body and an end of the second body.
 3. The burner as claimedin claim 1, wherein an oxidizing agent injection port is formed at asidewall of the burner housing, and a passage is formed between an innerperipheral surface of the burner housing and an outer peripheral surfaceof the second body to allow the oxidizing agent to be fed into the firstbody through the oxidizing agent injection port.
 4. The burner asclaimed in claim 1, further comprising a fuel injection port, whichforms a path for feeding the fuel towards an inner peripheral surface ofthe second body.
 5. The burner as claimed in claim 4, further comprisinga center plug inserted into the second body such that a cavity iscoupled to the fuel injection port is formed between the second body andthe center plug, wherein a fuel exhaust port is formed between thecavity and an end of the second body.
 6. The burner as claimed in claim5, wherein a vacuum region is formed between the fuel exhaust port andthe end of the second body as the oxidizing agent is fed into the firstbody so that the fuel provided in the cavity is exhausted into thevacuum region through the fuel exhaust port.
 7. The burner as claimed inclaim 1, further comprising a center plug inserted into the second bodyand extending lengthwise along the burner housing, wherein an end of thefirst body is closed by an end of the center plug, and the sprayingports are formed at the end of the center plug.
 8. The burner as claimedin claim 7, further comprising a second injection port for exhaustingthe fuel fed into the center plug to the exterior through a center ofthe spraying ports.
 9. The burner as claimed in claim 7, wherein avacuum region is formed between an outer peripheral surface of thecenter plug and an inner peripheral surface of the second body as theoxidizing agent is fed into the first body.
 10. The burner as claimed inclaim 7, wherein the oxidizing agent is mixed with the fuel in a regionformed between an outer peripheral surface of the center plug and aninner peripheral surface of the first body as the oxidizing agent is fedinto the first body.
 11. The burner as claimed in claim 1, furthercomprising a guide housing for receiving the burner housing, the firstbody and the second body therein.
 12. The burner as claimed in claim 11,further comprising a second oxidizing agent injection port formed at asidewall of the guide housing, wherein the oxidizing agent introducedinto the guide housing is exhausted to the exterior through a pluralityof guide holes formed around the spraying ports.
 13. A burner used forfabricating an optical fiber preform, the burner comprising: a burnerhousing; a first body including a plurality of spraying ports, at leasta part of the first body being accommodated in the burner housing; asecond body aligned in a length direction of the first body, at least apart of the second body being accommodated in the burner housing wherethe first body is spaced from the second body 103 by a predetermineddistance in order to form an oxidizing agent port therebetween; and afuel injection port that extends into the second body to allow the fuelto be injected through the second body and fed into the first body. 14.The burner as claimed in claim 13, wherein the oxidizing agent port isformed along an outer circumferential portion of the second body so thata passage is formed between an outer peripheral surface of the secondbody and an inner peripheral surface of the burner housing in order toconnect an injection port to the oxidizing agent port.
 15. The burner asclaimed in claim 13, further comprising a center plug inserted into thesecond body such that a cavity is coupled to the fuel injection port isformed between the second body and the center plug, wherein a fuelexhaust port is formed between the cavity and an end of the second body.16. The burner as claimed in claim 15, wherein a vacuum region is formedbetween the fuel exhaust port and the end of the second body as theoxidizing agent is fed into the first body so that the fuel provided inthe cavity is exhausted into the vacuum region through the fuel exhaustport.
 17. The burner as claimed in claim 12, further comprising a centerplug inserted into the second body and extending lengthwise along theburner housing, wherein an end of the first body is closed by an end ofthe center plug, and the spraying ports are formed at the end of thecenter plug.